Radiant energy control system for missile guidance



May 8 1956 J. v. sToDDARD 2,745,095

MISSILE GUIDANCE RADIANT ENERGY CONTROL SYSTEM FOR 2 Sheets-Sheet l Filed Sept. 4, 1947 PmNJ/ May 8, 1956 J. v. STODDARD 2,745,095

RADIANT ENERGY CONTROL SYSTEM FOR MISSILE GUIDANCE Filed Sept. 4, 1947 2 Sheets-Sheet, 2

QU/Y

JAMES V. STDD/IRD AUTOMATIC T BY lMANUAL ATTCJRN EY United States Patentl RADIANT ENERGY CONTROL SYSTEM FOR IVIISSILE GUIDANCE James V. Stoddard, St. Josephs, N.`Y., assignor to the United States of America as represented by the Secretary of War Application September 4, 1947, Serial No. 772,040

Claims. (Cl. 343-6) (Granted under Title 35, U. S. Code (1952), sec. 266) matically tracked by a ground radar; and by means of visual sighting and hand control, the projectile is brought by manual control into the neighborhood of the target and in the path of the radar beam. Once the projectile is in the radar beam, the control guiding the projectile is taken over by special apparatus added to the radar set and automatically directed into the target. On the radar oscilloscope there will appear a range pip corresponding to the echo from the target and simultaneously, a range pip corresponding to the echo from the projectile will appear. When both pips coincide, the projectile is manually detonated.

This and other objects are attained by the novel arrangement of devices and method hereinafter described and illustrated by the accompanying drawings, forming a part hereof, and in which- Fig. 1 is a diagrammatic view of a projectile-used in connection with the invention.

Fig. 2 is a block diagram of the radio transmitter control and radar apparatus.

Fig. 3 is a block diagram schematic showinghow the invention may be appliedto a conventional radar set of the automatic tracking type.

, Referring to the drawings, in Fig. l is shown a diagrammatic view of a projectile, which contains a rocket motor 1 for propulsion. The rocket motor comprises cells containings the propellant. The cells are arranged to burn in series to give the projectile suicient speed to maintain Steerage-Way during its ight to the target at an average speed of 20D-300 yards per'second for a period of least 60 seconds maximum time of ight.

Mounted on the projectile is a radio receiver unit 2 of the type used for the radio control of target planes. The source of electrical power is a wind-driven generator or a paste type storage battery. Aileron, rudder and elevators mounted on the wings and tail assembly of the projectile control the direction of ight. Due to the high velocity of the projectile the movement required for control will be slight, but greater force will be required to operate the controls. The trailing edge of the wings 3 and tail assembly, where practical, are surfaced with copper to provide an antenna for the radio receiver.

l The projectile may be stabilized in ight by either a pendulum type relay switch or a small gyro stabilizer in order to prevent its rotation 4when in mid-air as there at the same time.

The bursting charges 4 comprises from 10 to 20 pounds of TNT depending upon the thickness of the case restraining it. The charge is detonated electrically through the use of a relay switch operated by the radio receiver in the projectile. The steel casing should be serrated slightly on the interior surface to provide for greater fragmentation without too great a loss of tensile strength.

The projectile is launched by a standard type rocket launcher mounted on a carriage capable of 6400 mil traverse and fitted with an elevation rack and traversing device graduated in mils so that the launcher can be positioned to send the projectile into a radar beam with a minimum loss of time.

The projectile is controlled by a radio transmitter similar to the transmitter used for the radio control of target planes.

In this specication the term radar is used in the conventional sense to designate a radio pulse-echo object locating device. The term tracking is used to designate the act of following a moving target so that at any instant information is available as to azimuth, elevation, height, and range.

l'n conventional radar systems of the automatic tracking type, a set may be said to be focused on the object selected as a target and being tracked, since echoes coming from objects either nearer the set or beyond the target are blocked out of the receiving channels used for automatically positioning the antenna system. Echoes coming from objects within the selected depth in range, including the target, are passed through the proper channels. This process is known in the art as gating When the radar beam of an automatic tracking set is directed on a target, and when the target is included within a very narrow gate, the controls of the radar set may be thrown over from manual to automatic, and the set will follow the selected target automatically.

The present invention takes advantage of this gating characteristic of a radar set which permits it to be focused on one object in the beam to the exclusion of all others. According to the invention a second gate is provided to exclude echoes from all objects in the radar beam except those included within the second gate. A separate channel is added to the conventional system and adapted to pass echo signals originating in the second gated region.

-- By this means the same set may be focused on two diiferent objects at different ranges in the same radar beam Thus for example in the case of a rocket projectile within the radar beam, the gate of the second channel may be set to include the rocket. Echo signals from the rocket passing through the common un'- gated part of the radio receiver are rejected by the gate set for the target in the normal channel, but are accepted is no means of reversing control signals should the projec- J tile rotate degrees.

` diagram 18. The

by the gate set for the rocket in the second channel. Error voltages are developed in both channels by the usual means provided for that purpose; that for the target being used for-automatic tracking of the target, while that for the rocket is used to automatically guide the rocket along the axis of the radar beam into the target.

Referring now to Fig. 3 which is a block diagram schematic showing how the invention may be applied to a conventional radar set of the automatic tracking type, the operation of the conventional set will rst be briefly described. f

The radar projector 10 includes a dipole antenna 11, a

reflector 12, spinner motor 13 and reference generator 14. The axis of the reector 15 is directed at the airplane target 16. The axis of the radio beam 17 is offset fromthe reflector axis 15 about 1114i pole.

17 is appreciably greater than along the reflector axis 1 5 as indicatedby the intercept 19 on the polar radiation antenna dipole is rotated by the spinner' due to dissyminetry in thedi-` Thus the radiation intensity along` the oiset axisk motor 13 so the radiation axis 17 sweeps out a cone in space. This is known as conical scanning. An object, such as target 16, lying on the reector axis receives radiation of constant intensity as measured by the intercept 19 during rotation. But anfobject, say20, on .the radio axis 17 in the position shown, would receive maximum radia tion in that position and a minimum when the spinnerV motor rotates the antenna a half revolution. If the target is off the reflector axis,rthe intensity of the radio pulses intercepted will vary sinusoidally as the dipole revolves. The intensity of the reected echoeswill therefore also Vvary sinusoidally and the amplitude variation-will increase with the displacement of the targetgthat is with the target I error. v

Thereectedecho signals when detected in the radio receiver 21,arnplied in the intermediate frequency chan nel 25, and rectified in the servo channel 26, produce an alternating current voltage whosefrequency corresponds to the speed of rotationV of the spinner motor and whose amplitude is proportional to the displacement of the target from the axis of the reflector. This voltage, is known in the art as the error voltage.

The small two phase alternating current generator 14 mounted on the antenna axis revolves with the spinner motor and generatestwo sine wave reference voltages at right angles to each other. The rotor of the generator is adjusted so that the voltage maxima occur in the horizontal and vertical planes respectively and serverto dis` tinguish and resolve error signals in azimuth and elevation. The reference voltages are combined with the error voltage in the automatic tracking unit 27 where a 'tube combination known in the art as commutator tubes` converts the combined input into a direct current output'. whose direction is dependent on the direction of displacement error vof the target from the axis of the reilector and whose magnitude is proportional to that displacement. Separate direct currents are developed for azimuth error and elevation error and are applied tothe eld circuits ofk the azimuth and elevation motor generatorfsets 28 i and 29 respectively which in turn drive the azimuth and elevation motors 30 and 31. These motors move the antenna in azimuth and elevation in a direction tol eliminate the error voltageand thus automatically bring the reflector axis in line with the target.

The range unit 32 produces thek timing trigger pulsesY and@ gates which make accurate range measurements pos-r sible. A crystal oscillator in the range unit produces a master'fimiug frequencywith which all major circuit actionsin the radar set are synchronized. Thus the magne-` tron pulses in the transmitter 23 occur at the same instant that the range Oscilloscopes 35 and 36 in the range indicator 37 and-plan position indicator oscilloscope39, traces start vand lthe automatic tracking circuits are gated and energized onlytfor that` fraction of a microsecond represented by'a 50 yard depth in range generated by the nar'- row-narrow gate unit 34.designated as the N2 gate. The narrow gate unit 33 produces a positivev pulse of variable i gate depth 52. j Y

ldetonating the charge.

The foregoing description is a brief outline of the various components and functions of a conventional'radar set provided with the features necessary for automatic tracking'and is not part of the present invention.

According to the invention a second channel Vsubstantially like that justdescribed istapped into the receiving system at the point 42 between the lst-and 2nd intermediate frequency stages. The signal from thispoint is appliedto an ampliiier 25 just likeamplifer 25. All the components in the rst channel are'duplicated in the vsecond channel with the exception of theplan position indicator. Corresponding components are indicatedV by the same numbers primed. Y

By means of this second channel, a second object in the radarV beam, such as the rocket 50, may be located within the Adepth 51 of the N2 gate 34 by the adjustment of the range hand wheel 38 and displayed on the range Oscilloscopes 35' and 36 and may be tracked manually in range lby adjusting the range hairline ofthe fine range oscilloscope 36 to match the leading edge of the range pip. This may be done independently of the action of the first Vchannel which may be Vat the same time -automatically tracking the airplane target16.,within the N The manual tracking of the rocket just described may be transferred to automatic tracking by utilizing the automatic tracking unit V27 in a manner similar to the automatic tracking unit `27 in the first channel. This may be accomplished by substituting the directional relays 55 and 56 for the servomotor generator sets 28 4and 29. These relays may be of the polarized type having operating coils 57 andA 58 which cause the pvoted armatures 59 and 60 to close contacts 61 and 62 or 63 and 64 depending on the direction ,of the magnetizing currents in the coils. Closure of-any one of the relay contacts causes the rocket control transmitter to send out a modulated signal,

, the frequency of which isdeterrnined by the contact being closed. Five modulatingffrequencies areused, four for guiding the rocket in azimuth and elevation and one for Any group of frequencies preferred may be selected for the purpose. For example 500, 750, 100, -l 500, and 2000 may be used. 'Ihese frequencies may be generated by an oscillator 72 in a conventional circuit having inductances 73 and 74 and tuning condensers width controlled by a potentiometer which rotates with the range pointer on the range indicator 35 and range handwheel 38. The range indicator unit provides neiand coarse range data and aligns the range hairlines on the range Oscilloscopes with a selected target echo.v It posi-` tions the narrow gate delay potentiometer so that the output of the` potentiometer illuminates theV `2000 yard oscilloscope 36, and triggers the N2 gate unit at the range of the ydesired target. The positioning of the'range hairlines, potentiometers, etc., is controlled either manually by the range hand wheel 38 or automatically by range Y motors and asociated gearing not shown. n ofV the intermediate frequency amplifier 25 divides at the point 40 between the 5th and 6th stages, part going into the servo channel 26 as described and part continuing through the range channel 41 where the .pulses are detected, amplified and applied to the range indicator and4 f plan position oscilloscope.

The outputl 75, 76, 77, 78 and 79 each of such capacity that when switched into circuit automatically by the relay contacts or manually by the manual control device 82 the desired t frequencies vare generated. The switch 81 transfers from manual to'automatic control.

It is necessary that only one condenser of the modulating oscillator be connected in circuit at a time; Since in automatic operation errors usually exist simultaneously in bothazimuth and elevation,-both relays are usuallyactive atvthe same time. Simultaneous operation is'prevented by the introduction ofa small motor operated earn 90 which closes contacts 91 and 92 alternately.

Thus when the second channel is set for automatic operation, error signals are generatedv by the echoes reflectcd'from the rocket `50 proportional to the rocket error 53. VThese signals are developed in the second channel yand applied to the rocket automatic tracking unit 27' which energizes the directional vrelays 55 and 56 alternately to send out modulated signals on the rocket transmitter. These signals are received by the rocket receiverY and applied to control the rocketV ,steering elementsl selected bythe modulating frequency and determined bythe actomatic Vtracking unit. The rocket is thus guided toward the axis of therrradar beam until the error voltage disappears. *The rocket continues to be guided along the axis of the radar beam until it reaches Vthe target, whichevent isindicatedon the range indica'- tor.A The push button 'is then actuated bythe operator which sends out ac'ontrol frequencygto. detonatc the bursting charge in the rocket.` v

The manual control device 82 hasa centralcontact member 83 carried on the end of the operating arm (not shown) which simulates the pilots stick in an aircraft. By manipulating the stick the central contact 83 may be brought intoengagement with right or "1eft contacts 84 or 8S or with up or down contacts 86 or 87. When the transfer switchl is in the manual position, the closure of any one of thev contacts in the manual control device connects in circuit one of the condensers of the modulating oscillator 72 to generate the desired control frequency.

i lclaim:

1. In combination with an object locating device of the pulse-echo type having a narrow radio beam with means for conical scanning and a normal receiving channel adapted to track ia moving target automatically, means for simultaneously tracking a second object in range moving `within the radio beam, said second tracking means comprising a second receiving channel included as part of the object locating device and connected to the normal receiving channel at an intermediate point in the intermediate frequency amplier, said second receiving channel including means for detecting and amplifying echo pulses and for displaying said pulses on a range oscilloscope, and means for producing a very narrow gate at the range of the second object such that all echo signals coming from objects within the radio beam are rejected except those from the said second object within the narrow gate.

2. In combination with an object locating device of the pulse-echo type having a narrow radio beam with means for conical scanning and adapted to track a moving target automatically, means for automatically guiding a rocket projectile along the axis of the radio beam, said guiding means comprising a second receiving channel as an added component to the object locating device, a radio transmitter adapted to send out signals for controlling the rocket, a radio receiver within the rocket responsive to said transmitter for steering the rocket, means for manually controlling the transmitter and directional relay means actuated by the output of said second receiving channel for automatically controlling the transmitter, said second receiving channel including means for producing a narrow gate at the range of the rocket and adapted to reject all echo signals coming from objects within the radio beam except those from the rocket included within said gate, means for amplifying error signals derived from said conical scanning, and means for converting said error signals into equivalent directional servo voltages for energizing said directional relays whereby the rocket is guided along the radio beam so that the error signals are nullified.

3. In combination with an object locating device of the pulse-echo type having a narrow radio beam with means for conical scanning and adapted to track a moving target automatically, means for automatically guiding a rocket projectile along the axis of the radio beam into said moving target and means for detonating the explosive charge in said projectile, said guiding means comprising a second receiving channel connected to the normal receiving channel of the object locating device and excited therefrom, a radio transmitter adapted to radiate any one of a number of predetermined modulated signals, a radio receiver within the rocket adapted to receive and distribute any one of the said modulated signals for steering the rocket and for detonating the explosive, means for manually selecting and activating any one of said modulated signals for steering, means for manually activating the detonating frequency, and directional relay means actuated by the output of said second receiving channel adapted to automaticaly select and activate the proper modulation signal, said second receiving channel including means for producing a narrow gate at the range of the rocket and adapted to reject all echo signals corning from objects within the radio beam except those from the rocket included within said gate, means for amplifying error signals derived from said conical scanning and means for converting said error signals into equivalent servo voltages for energizing said ydirectional relays, whereby the rocket is guided along the radio beam so that the said error signals are reduced to zero.

4. In an object locating system of the pulse echo type, means including an antenna for transmitting a narrow radio beam, means for automatically tracking a moving target with said radio beam, and means for simultaneously and automatically guiding a missile to travel within said radio beam and toward the target, said guiding means comprising a receiving channel excited from said antenna, said receiving channel including a narrow gate and means for setting said narrow .gate at a range to include said missile, a second automatic tracking means responsive to echoes from said missile within said narrow gate, and a radio transmitter controlled by said second automatic tracking means, said last-mentioned transmitter emitting a signal which controls the direction of movement of said missile.

5. A remote control system comprising means for transmitting a narrow beam of pulses, means responsive to the reception of echo signals reected from a remote first body for causing said beam to be directed toward said iirst body, and means for guiding a second remote body to travel in the direction of said beam, said last-mentioned means comprising a second transmitter whose signal controls the direction of motion of said second body, and a second receiver responsive to the pulses of said transmitted narrow beam retiected from said second body to control said second transmitter.

6. A remote control system comprising means for transmitting a narrow beam of pulses, means responsive to the reception of echoes reflected from a first remote body for causing said beam to be directed toward said first body, and means for guiding a second remote body to travel toward said tirst remote body, said last-mentioned means comprising a second transmitter whose signal controls the direction of motion of said second body, and a second receiver responsive to the pulses of said transmitted narrow beam reected from said second body to control said second transmitter.

7. A remote control system comprising means for transmitting a narrow beam of pulses, means responsive to the reception of echoes retiected from a iirst remote body for causing said beam to be directed toward said lirst body, and means for guiding a second remote body to travel toward said first remote body, said last-mentioned means comprising second receiver means for selecting echoes from said narrow beam of transmitted pulses reected from said second remote body, a second transmitter whose signal controls the direction of movement of said second remote body, and directional relay means interposed between said receiver means and said second transmitter for controlling said second transmitter responsive to the echo signals reiiected from said second remote body.

8. In combination, highly directional means to transmit pulses and receive echoes thereof, means to select echoes reflected from a first remote body, means associated with said selective means for continuously causing said pulse transmission to be directed toward said iirst remote body, and means for guiding a second remote body to travel in the direction of said directional pulse transmission, said last-mentioned means comprising a second selective means for selecting echoes from said highly directional transmitted pulses reflected from said second remote body, a second transmitter whose signal controls the direction or" movement of said second remote body, and means associated with said second selective means and responsive to the reception of echoes refiected from said second remote body for controlling said second transmitter.

9. A remote control system of the pulse-echo type comprising means for transmitting a narrow beam of radio pulses, means for continuously causing said beam to be substantially aligned withV a rst moving body, and means for simultaneously guiding a second moving body in the direction of said beam, said lastfmentioned means including a second transmitter whose signal controls the direction of movement of said second moving body, and a receiver responsive to said narrow beam of radio pulses re- Vected from said second moving body for controlling the from said highly directional transmitting means rcected.

8\ Y from the second moving body and a secondtransmitter whose signal controls the; direction `of movement of ,said second moving body, said second transmitter beingcontrolledrby the response of said receivrfto determine the direction of movement of Asaid second moving body..V

' ,Y References cned in :he 'fue .criminelen Y UNITED STATES PATENrs- 

